The choice between this two boils down to personal preferences.

Here are a few tidbits of maybe useful information (off the top of my head):

1. I personally prefer the Tivo Stream 4K remote, because the rubber buttons are more pleasant to interact with than the plasticky buttons on the ONN 4K remote. Also the Tivo Stream 4k remote is more ergonomically shaped. The ONN 4K button layout is better, but the ONN remote is a bit too "thick" (high), for my personal taste--flatter remotes just fit better in MY hands.
2. The ONN is noticeably snappier (faster). Not sure if this is because of the chipset, or because of Android 10 vs 9.
3. The ONN is very stock Android (nice). With the Tivo Stream 4K, if you don't care for the Tivo "features" you have to De-Tivo it.
4. The Tivo Stream 4K has a Micro USB AND a USB C port. So it's more flexible for adding peripherals than the ONN which has the single Micro USB port only.
5. I believe right now, the ONN 4K is configured with HDR always on (without the ability to turn this off). Initially when Tivo Stream 4K launched, this was also the case, but this has since been fixed via software? (I no longer have a Stream 4K to confirm). Software support for the Tivo Stream 4K may be noticeable better than what you can expect from the ONN. (I was briefly in the Tivo Stream 4K beta program, so I know at that time they were active with fixing problems).
6. Overall I think the ONN device is a fantastic value proposition given it's below $30 price-point. I prefer the snappy response on this device. However, I encountered a weird snafu with the way it was breaking my audio connection of my TV to my Soundbar (something with it's CEC implementation). IF Tivo plans to keep on supporting the Tivo Stream 4K, and IF you can score one for a cheap price (Tivo's website has it for ~$25 with a 15% off code...some Walmarts have them on clearance for $19.xx), then MAYBE the Tivo Stream 4K is the better buy? I guess it all depends on what's important to you, and what works best with your setup.
7. Edit: Also I couldn't get the ONN to control my TV (TCL) via IR. I went through the setup, and TCL is on the list..but programing their remote to control other equipment seems hit or miss at this point.

Good luck!

So far after1 day It's a very solid device, pretty equal to the Tivo Stream 4k. Perhaps a bit snappier. 2nd best Android TV remote I've used. I like it better than the Tivo one but not as much as the Shield remote. It has the new Android TV UI which I like. There are some app updates needed. Vudu doesn't have 4K, Movies Anywhere doesn't display video, standard for these kinds of app with new devices. It may be too early to really recommend the ONN until we see how well supported it will be. It's also probably the best device ever released at the $30 price point.

I talked about my experience here . I ended up having to return it.

The tivo does not allow you to use the discover or apps tabs. You are stuck with home and the ad carousel

It's like the Tivo, without any special features. That's pretty much all there is to it.

Loving it, best $30 I have ever spent on a streaming device. I am using Locast even though I don't live in a covered area. Also using it to watch BBC iPlayer and My5. Easiest setup to accomplish this, I have ever had. Will be ditching all my Fire TVs and Roku's. It's fast and only will get better as more Android TV apks come out.

Well the obvious is Onn has an oversized powerbrick from the 90s with a fixed cable and an unnecessary long hdmi cable is used connect it when there are no actual ports on it. Other than that I don't see any point of buying it because I don't see it how Walmart is better than Tivo in the software side of things.